Linear antifriction bearing

ABSTRACT

A linear antifriction bearing arrangement including two relatively movable machine members and a plurality of cylindrical bearing cartridges mounted for providing linear movement of one member with respect to another. Each bearing cartridge includes a raceway and interconnected internal passageways forming a channel for recirculating a plurality of bearing balls. The cartridges include removable retainer plates for retaining and guiding the bearing balls through the recirculation channels. The bearing cartridges are slidably journaled in one of the machine members and are operable to support the other machine member for relative linear movement. The arrangement provides for ease of preloading to provide zero lateral play and the individual cartridges are self-aligning to provide even load distribution.

United States Patent 1 Anderson et al.

[ 1Marc11 20, 1973 (54] LINEAR ANTIFRICTION BEARING Appl. No.: 109,280

[52] US. Cl. ..308/6 C [51] llnt. Cl. ..Fl6c 29/06 [58] Field of Search..308/6 C, 6 R, 194, 3 R, 3 A, 308/176, 185

[56] References Cited UNITED STATES PATENTS 3,071,418 l/l963 Hayes..308/6 C 3,560,061 2/1971 Shaw, Jr. ..308/6 C 3,545,826 12/1970 Mageeet al. ..308/6 C 3,608,985 9/1971 Swanson ..308/6 C 3,398,999 8/1968Halvorsenm ..308/6 C 3,588,200 6/1971 Thomsonm. ..308/6 R 2,352,9117/1944 Osplack ..308/6 R 3,008,774 11/1961 Morris et al. ...308/3 A3,113,807 12/1963 Polidor ..308/6 R 3,342,534 9/1967 King ..308/6 R3,436,132 4/1969 Wiesler ..308/6 C 2,863,705 12/1958 Gluchowicz 1 1..308/6 R 3,484,944 12/1969 Pryshlak .308/6 R Primary ExaminerCharles J.Myhre Assistant Examiner-Barry Grossman Att0rney--Michael E. Martin [57]ABSTRACT A linear antifriction bearing arrangement including tworelatively movable machine members and a plurality of cylindricalbearing cartridges mounted for providing linear movement of one memberwith respect to another. Each bearing cartridge includes a raceway andinterconnected internal passageways forming a channel for recirculatinga plurality of bearing balls. The cartridges include removable retainerplates for retaining and guiding the bearing balls through therecirculation channels. The bearing cartridges are slidably journaled inone of the machine members and are operable to support the other machinemember for relative linear movement. The arrangement provides for easeof preloading to provide zero lateral play and the individual cartridgesare self-aligning to provide even load distribution.

7 Claims, 6 Drawing Figures LINEAR ANTIFRICTION BEARING BACKGROUND OFTHE INVENTION Various types of bearing arrangements are known forproviding for linear motion of one machine element with respect toanother. In the art of machine tools, for example, it is desirable toprovide for precise low friction linear movement of a work supportingtable with respect to the frame of the machine or conversely movement ofthe tool supporting member with respect to the work. Another applicationof linear motion bearings is found in automated apparatus for makingsolderless connections of electrical conductors to terminal boards. Inautomatic conductor wrapping apparatus the conductor wrapping tools andconductor guiding devices must be moved with precision and with relativeease and minimal deflection of the wrapping tool supports is required.

Known types of linear motion bearing arrangements used in the abovementioned applications include the type disclosed in US. Pat. No.2,452,117 which is characterized by a tubular sleeve type of bearingcartridge containing recirculating antifriction bearing elements andadapted to be linearly slidable on a shaft. The disadvantage of thistype of arrangement is that the shaft or supporting member must remainunsupported over the traversal distance of the sleeve. Moreover, it isdifficult to preload and to determine the amount of preload with thetubular sleeve bearing arrangement.

Another type of linear bearing arrangement is disclosed in US. Pat. No.3,008,774 wherein a plurality of bearing cartridges of the recirculatingball type are arranged to support one member movably with respect toanother. Although the particular arrangement disclosed provideswedge-shaped supports for preload ad'- justment, the entire arrangementis rather complex and the bearing cartridges do not lend themselves to aselfaligning type of mounting.

Known types of linear bearing arrangements are also somewhat lacking inproviding for easy insertion and removal of the individual bearingcartridges with respect to the complete assembly. This is a particularlybothersome problem when heavy machine members are involved as componentsof the bearing arrangement or when it is undesirable to disturb therelative positions of the machine components.

SUMMARY OF THE INVENTION The present invention provides for an improvedlinear antifriction bearing arrangement whereby a plurality of bearingcartridges are removably mounted on a machine component and are adaptedto support another machine component for reversible rectilinear motion.In the linear antifriction bearing of the present invention, eachindividual bearing cartridge is adapted to recirculate a number ofantifriction bearing elements through a recirculation channel which issimple in construction and reliable in operation.

The present invention further provides for a linear antifriction bearingarrangement which may be preloaded a controlled and measured amount toeliminate any unwanted loose motion between machine components.

In accordance with the present invention there is also provided a linearbearing arrangement in which individual bearing cartridges by virtue oftheir cylindrical shape are inherently self-aligning.

Moreover, the present invention provides a linear antifriction bearingarrangement including a plurality of bearing cartridges which areindividually accessible for removal and replacement without disturbingthe machine components whichthey are supporting.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a linearantifriction bearing arrangement in accordance with the presentinvention.

FIG. 2 is a transverse elevation of the bearing arrangement of FIG. 1.

FIG. 3 is a view taken along the line 3-3 of FIG. 1.

FIG. 4 is a view taken along the line 4-4 of FIG. 2.

FIG. 5 is a perspective cutaway view of one of the bearing cartridgeunits.

FIG. 6 is a transverse elevation of an alternate embodiment of a linearantifriction bearing arrangement in accordance with the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2 alinear antifriction bearing arrangement is illustrated as comprising amachine component or member 10 which is linearly movable with respect toanother machine member 12. In use in a machine tool or the like themember 10 might be considered to be fixed or comprise a part of themachine frame and the member 12 might comprise the carriage or a movabletable. The function of the two members 10 and 12 may be reversed, ofcourse, as it will be assumed to be merely a design choice. The sameinterchangeability of function will be assumed to be easily achievedwith the embodiment of FIG. 6.

The member 12 has a generally U-shaped configuration defined by thefurcations l4 and 16 which include pairs of opposed cylindrical bores 18and 20, spaced apart. Located in each of the bores 18 and 20 in closefitting relationship are recirculating ball bearing cartridges,generally designated by the numeral 22. The bearing cartridges 22 areretained within their respective bores in the member 12 by removablecover members 24 suitably fastened to the member 12 and having pilotdiameter portions 26. As will be noted from the exemplary cutawayportion of FIGS. 1 and 2 shims 28 of various thicknesses may beinterposed between the end face 30 of the cover 24 and the end face ofthe bearing cartridge 22.

Referring to FIGS. 1 through 5 the bearing cartridges 22 each comprise acylindrical support block 32 dimensioned to be slidably journaled butclosely fitted in the bores 18 and 20. The support blocks 32 include aplurality of antifriction bearing elements in the form of balls 34 whichare operable to circulate reversibly in a channel formed by the passage36, intersecting passages 38 and 40, and the oppositely inclined planarsurfaces 42 and 44. The surfaces 42 and 44 also form a groove comprisinga raceway for supporting the balls 34 when they are carrying the load ofthe members 10 and 12 with respect to each other. The passages 36, 38and may be formed by a conventional boring or drilling process in viewof the fact that the slight ridges or discontinuities formed by theintersections of the surfaces between the passage 36 and the respectivepassages 38 and 40 are not subject to high contact stresses from theballs 34 when the balls are rolling through these intersections.

The support blocks 32 also include two pins 46 of circular cross sectionpositioned to form contact surfaces for the balls 34 as they recirculatethrough the channel formed by the aforementioned passages and groove.The pins 46 provide for smooth rolling action of the balls as they rollthrough the passages 38 and 40 and into and out of the groove formed bythe surfaces 42 and 44. The balls 34 are retained in the groove and thepassage 36 in the support blocks 32 by substantially fiat retainingplates 48 which are fitted in slots 50 formed in the support blocks 32and bisecting the aforementioned ball recirculation channels. The plates48 are retained in each support block by a pin 52, FIGS. 3 and 4. Theplates 48 include a somewhat oval opening 54 defining the periphery ofthe recirculation path of the bearing balls 34. The cartridges 22 alsoinclude a passageway 56 for loading and removing balls 34 with respectto the recirculation channel. The passageway 56 is fitted with athreaded plug 58.

As shown in FIGS. 2 and 3 the member is provided with a pair of opposedelongated parallel grooves formed by the oppositely inclined planarsurfaces 60 and 62, said grooves forming raceways complementary to theraceways formed in each one of the cartridges 22. The member 10 alsoincludes slots 64 formed to provide clearance for the ball retainingplates 48. By providing the inclined surfaces 42 and 44 on the supportblocks 32 and the inclined surfaces 60 and 62 on the member 10 togetherwith provisions for prepositioning each pair of opposed cartridges 22longitudinally in their respective bores 20, contact of the balls 34 onall four surfaces is assured. This four-point contact provides forbetter load distribution and lower contact stresses on the respectivesurfaces forming the bearing raceways. Moreover, the surfaces 42, 44,60, and 62 may be formed by conventional machining techniques.

The cartridges 22, by being rotatably journaled in the bores 18 and tendto align themselves, upon assembly of the arrangement, so that theraceways formed on the cartridges 22 are parallel with the raceways inthe member 10 and hence more uniform loading is achieved of all balls inload bearing positions. In the arrangements of FIGS. 1 through 6 atleast two balls are in full load carrying position at all times andunder some conditions three are in full load carrying position as shownin the drawings. Also by providing the arrangement of the bores in themember 12, as shown, each bore of the pairs of bores 18 and 20 is easilymachined by conventional methods to be very closely in alignment withthe other bore of the pair.

An alternate embodiment of the present invention is illustrated in FIG.6. In the embodiment of FIG. 6 a member 70 is provided having agenerally U-shaped cross section forming the furcations 72 and 74 whichinclude bores 76 for journalling the bearing cartridges 22. Thearrangement of bearing cartridges in the embodiment of FIG. 6 may be inopposed spaced apart pairs as in the arrangement of FIGS. 1 through 5.The cartridges 22 located in the member 70 are retained in the bores 76by cover members 78 similar to the cover members 24 in FIGS. 1 and 2.The open area 80 between the furcations 72 and 74 provides for easyaccess to install -or remove the individual bearing cartridgcs 22 or toadjust the preload as in the embodiment of FIGS. 1 and 2. The bearingcartridges 22, in FIG. 6, are arranged to support the member withrespect to a member comprising a portion of a machine frame or the likeand represented by the portions 82 and 84 having opposed parallelgrooves, each groove formed by oppositely inclined planar surfaces 86and 88.

As previously mentioned the bearing arrangements of the presentinvention can be preloaded to a controlled and easily measured amount toremove all clearance or looseness of one of the linearly removablemembers with respect to the other. Upon assembly of the cartridges 22into their respective bores the thickness of shims 28 required to obtainzero clearance 1 or lateral looseness of the member 10 with respect tothe member 12 may be easily measured by obtaining the depth measurementfrom the surface 90 on the furcation 14 to the end face of the cartridge22 and subtracting from said measurement the height or length of pilotdiameter portion 26 on the cover members 28. To this measured shimthickness required for zero clearance shims of known thickness may beplaced between the cover members and the bearing cartridges to give adesired preload force in accordance with a predetermined relationshipbetween shim thickness and preload force values.

The bearing arrangements contemplated by the present invention alsoenjoy the advantage that when the bearing balls come into contact withthe raceways formed in the members 10 and 82-84, upon assembly of thebearing cartridges into the respective members 12 and 70, the cartridgestend to align themselves so that even load distribution is obtainedbetween the bearing balls and the raceways. This self-aligning featureof the bearing arrangements disclosed is enjoyed thanks to the rotatablejournalling of the cylindrical bearing cartridges in the members 12 and70.

What is claimed is:

1. In a linear antifriction bearing arrangement, in combination:

a first member including a pair of opposed elongated parallel groovesforming bearing raceways;

a second member linearly movable with respect to said first member andincluding a plurality of antifriction bearing cartridges removablymounted thereon, said bearing cartridges each comprising a cylindricalsupport block including a groove formed thereon and a plurality ofantifriction bearing elements operable to roll along said groove on saidsupport block;

said second member having said plurality of bearin cartridges soarranged thereon that at least one bearing cartridge is disposedadjacent each groove of said pair of opposed parallel grooves on saidfirst member and said antifriction bearing elements of each of saidplurality of bearing cartridges are engaged with the respective adjacentgroove on said first member whereby said second member is supported forlinear movement with respect to said first member, said second memberincluding cylindrical bores dimensioned to receive said support blocksin close fitting relationship whereby said support blocks are eachoperable, upon engagement of their anti-friction bearing elements withsaid opposed parallel grooves on said first member, to rotate in saidbores to align said grooves on said support blocks to be parallel withsaid pair of opposed parallel grooves on said first member; and,

means located in said bores operable to position said support blocks toprovide forcible engagement of said antifriction bearing elements withsaid pair of opposed parallel grooves on said first member and saidgrooves on said support blocks thereby to pre- 5. The invention setforth in claim 4 wherein: said bearing cartridges each includepassageways formed therein and interconnected with said groove portionforming said bearing raceway to define a recirculation channel for saidantifriction bearing elements and said bearing cartridges includeretaining members for said antifriction bearing elements, said retainingmembers comprising load said linear antifriction bearing arrangement. 102. The invention set forth in claim 1 wherein: said second memberincludes removable cover members for covering said cylindrical bores toretain substfmtially pletes m e in e bearing said cylindrical supportblocks therein and said 6 f r h e i g i F Q Q channeleinvention set ortinc aim w erem: 2 :3; i; %;f;: gg 'g f i gf said retaining membersinclude substantially oval openings formed therein and defining theposed m Said between cylmdncal periphery of a recirculation path forsaid antifricport blocks and said cover members.

tion bearing elements. In a near annfnctlon bearmg arrangement m 7. In alinear antifriction bearing arrangement in combination combination: afirst member provided with two pairs of oppositely a fi t member i l dia pair of opposed elongated inclined planar surfaces each of said pairsof oppositely parallel groovesforming bearingraceways; inclined planarsurfaces being arranged on said a second member linearly movable withrespect to member to form Opposed Parallel grooves Provldmg said firstmember and including a plurality of anbearing raceways;

tifriction bearing cartridges removably mounted a second member having aplurality of antifriction thereon, said bearing cartridges eachcomprising a bearing cartridges mounted thereon, each of said bearingcartridges having a recirculation channel and a plurality ofantifriction bearing elements cylindrical support block including agroove formed on one end thereof and a plurality of antifriction bearingelements operable to roll along located in and movable through saidrecirculation said groove on said support block; Channel, a Portion ofSaid recirculation Channel said second member having said plurality ofbearing comprising a groove forming a bearing raceway for cartridges soarranged thereon that at least one said antifriction bearing elementswherein said anbearing cartridge is disposed adjacent each groovetifriction bearing elements are operable to be in a of said pair ofopposed parallel grooves on said load carrying position, said bearingcartridges first member and said antifriction bearing elebeing rotatablysupported on said second member ments of each of said plurality ofbearing carwhereby at least one cartridge is operable to have tridgesare engaged with the respective adjacent its antifriction bearingelements make rolling congroo e on said first member whereby said secondtact with said oppositely inclined surfaces of each member s S ppor edfor in ar movement with of said pair of oppositely inclined surfaces onsaid respect to Said first member; and, fi member h b id fi member isaid second member including cylindrical bores ported for linearmovement with respect to said dimensioned l'eeeive Said pp blocks inSecond b close fitting relationship whereby said support 4.The inventionset forth in claim3wherein: blocks are each Operable, P engagement ofsaid bearing raceways formed on said bearing car; their antifrictionbearing elements said Optridges comprise a pair of oppositely inclinedPosed Parallel grooves Said first member, to planar surfaces and saidantifriction bearing ele rotate in Said bores to align i greoveson Saidments are operable to engage each of said oppp blocks to be P e wlthSaid P of P positely inclined planar surfaces on said bearing Posedparallelgrooves on 531d first member cartridges and each of saidoppositely inclined

1. In a linear antifriction bearing arrangement, in combination: a firstmember including a pair of opposed elongated parallel grooves formingbearing raceways; a second member linearly movable with respect to saidfirst member and including a plurality of antifriction bearingcartridges removably mounted thereon, said bearing cartridges eachcomprising a cylindrical support block including a groove formed thereonand a plurality of antifriction bearing elements operable to roll alongsaid groove on said support block; said second member having saidplurality of bearing cartridges so arranged thereon that at least onebearing cartridge is disposed adjacent each groove of said pair ofopposed parallel grooves on said first member and said antifrictionbearing elements of each of said plurality of bearing cartridges areengaged with the respective adjacent groove on said first member wherebysaid second member is supported for linear movement with respect to saidfirst member, said second member including cylindrical bores dimensionedto receive said support blocks in close fitting relationship wherebysaid support blocks are each operable, upon engagement of theirantifriction bearing elements with said opposed parallel grooves on saidfirst member, to rotate in said bores to align said grooves on saidsupport blocks to be parallel with said pair of opposed parallel grooveson said first member; and, means located in said bores operable toposition said support blocks to provide forcible engagement of saidantifriction bearing elements with said pair of opposed parallel grooveson said first member and said grooves on said support blocks thereby topreload said linear antifriction bearing arrangement.
 2. The inventionset forth in claim 1 wherein: said second member includes removablecover members for covering said cylindrical bores to retain saidcylindrical support blocks therein and said means for positioning saidcylindrical support blocks in said bores includes spacer meansinterposed in said bores between said cylindrical support blocks andsaid cover members.
 3. In a linear antifriction bearing arrangement, incombination: a first member provided with two pairs of oppositelyinclined planar surfaces each of said pairs of oppositely inclinedplanar surfaces being arranged on said member to form opposed parallelgrooves providing bearing raceways; a second member having a pluralityof antifriction bearing cartridges mounted thereon, each of said beariNgcartridges having a recirculation channel and a plurality ofantifriction bearing elements located in and movable through saidrecirculation channel, a portion of said recirculation channelcomprising a groove forming a bearing raceway for said antifrictionbearing elements wherein said antifriction bearing elements are operableto be in a load carrying position, said bearing cartridges beingrotatably supported on said second member whereby at least one cartridgeis operable to have its antifriction bearing elements make rollingcontact with said oppositely inclined surfaces of each of said pair ofoppositely inclined surfaces on said first member whereby said firstmember is supported for linear movement with respect to said secondmember.
 4. The invention set forth in claim 3 wherein: said bearingraceways formed on said bearing cartridges comprise a pair of oppositelyinclined planar surfaces and said antifriction bearing elements areoperable to engage each of said oppositely inclined planar surfaces onsaid bearing cartridges and each of said oppositely inclined planarsurfaces on said first member when said antifriction bearing elementsare in said load carrying position supporting said first member forlinear movement with respect to said second member.
 5. The invention setforth in claim 4 wherein: said bearing cartridges each includepassageways formed therein and interconnected with said groove portionforming said bearing raceway to define a recirculation channel for saidantifriction bearing elements and said bearing cartridges includeretaining members for said antifriction bearing elements, said retainingmembers comprising substantially flat plates mounted in said bearingcartridges and bisecting said recirculation channel.
 6. The inventionset forth in claim 5 wherein: said retaining members includesubstantially oval openings formed therein and defining the periphery ofa recirculation path for said antifriction bearing elements.
 7. In alinear antifriction bearing arrangement, in combination: a first memberincluding a pair of opposed elongated parallel grooves forming bearingraceways; a second member linearly movable with respect to said firstmember and including a plurality of antifriction bearing cartridgesremovably mounted thereon, said bearing cartridges each comprising acylindrical support block including a groove formed on one end thereofand a plurality of antifriction bearing elements operable to roll alongsaid groove on said support block; said second member having saidplurality of bearing cartridges so arranged thereon that at least onebearing cartridge is disposed adjacent each groove of said pair ofopposed parallel grooves on said first member and said antifrictionbearing elements of each of said plurality of bearing cartridges areengaged with the respective adjacent groove on said first member wherebysaid second member is supported for linear movement with respect to saidfirst member; and, said second member including cylindrical boresdimensioned to receive said support blocks in close fitting relationshipwhereby said support blocks are each operable, upon engagement of theirantifriction bearing elements with said opposed parallel grooves on saidfirst member, to rotate in said bores to align said grooves on saidsupport blocks to be parallel with said pair of opposed parallel grooveson said first member.